The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the semiconductor industry of utilized various methods and structures to form power supply circuits that operated from a single input voltage and supplied multiple output voltages. In some systems the power supplies were used to provide operating power for operating amplifiers such as amplifiers in an audio system. Typically, the prior power supply circuits used the input voltage as one operating supply for the amplifier and internally formed a second operating supply that had a value substantially equal to the input voltage but was negative relative to ground. One such power supply circuit was disclosed in U.S. Pat. No. 7,061,328 that issued to Tony Doy on Jun. 13, 2006. One problem with these prior power supply circuits was that the amplifier had to have a breakdown voltage large enough to sustain the difference between the two operating voltage values.
Accordingly, it is desirable to have a power supply circuit that provides a smaller differential between the maximum and minimum voltage values supplied by the power supply circuit and that can provide power to an audio amplifier system.
For simplicity and clarity of the illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action.